Dr Tatiana Ruis Bedoya’s paradigm-shifting doctoral dissertation, “Population Biology of Effector Repertoires in a Bacterial Plant Pathogen” has been awarded the Governor General’s Gold Medal, Canada’s highest award for graduate students.
Ruiz Bedoya has a life-long interest in understanding the natural world, spurred by exploring the Chicamocha Canyon near her home in Colombia. This led to jobs as a Park Ranger on Gorgona Island National Park and internships in Sweden studying ancient human DNA.
In her award-winning dissertation, Ruiz-Bedoya studied the bacterium Pseudomonas syringae in the Guttman/Desveaux labs. She finds this bacterium fascinating in terms of ecology (it lives in clouds, soil and plants) and in terms of evolution (it survives and thrives in all of those environments). This made it a great subject for Ruiz-Bedoya’s holistic approach to biology.
Ruiz-Bedoya focused on evolution of virulence factors (effectors) that allow P syringae to infect plants as a way of understanding host-pathogen interactions. P syringae creates a more favourable environment for growth in the extracellular environment of plant leaves by injecting large collections of diverse effectors into the host cell. Effectors interact with the plant immune system in an evolutionary arms race which can result in either resistance or susceptibility.
Some P syringae have evolved with 36 distinct effector proteins. In a technical tour de force, Ruiz-Bedoya isolated each effector into an individual strain of P syringae. Her goal was to study P syringae not as a single pathogen, but as a community of potential pathogens.
Her studies revealed that individual members of the population were unfit, but collective virulence allows the community to infect plants as a population-level phenotype. Ruiz-Bedoya’s collection of bar-coded effectors was then applied to assess the degree of redundancy and robustness of effector arsenals. Her systems-level approach revealed that synergistic interactions in the microbiome and genotype-fitness redundancy are mechanisms that can explain how diversity at multiple scales is maintained across environmental transitions.
Ruiz-Bedoya is an inspiring writer. In reviewing the literature for her dissertation, Ruiz-Bedoya’s supervisors encouraged her to tell the story of how she developed her research program as she reviewed the literature. Committee members told her frankly that they were inspired with new ideas as they read through her narrative.
Dr Ruiz-Bedoya is now applying her intellectual acumen to evolution of viruses as a post-doctoral fellow in Organismal and Evolutionary Biology at Harvard, with a further responsibilities in Biomedical Informatics at Harvard Medical School.
Winning an academic Gold Medal provoked bemused thoughts of knockout rounds from colleagues in Boston and family in Colombia. Even as they came to understand that there was no podium ceremony for the Gold Medal, they were impressed to learn that the award came from the Governor General, the King’s representative in Canada.
The content, clarity and originality of Ruiz-Bedoya’s work earned her this award. Congratulations, Tatiana!